Cured-in-place pipe lining sounds abstract until you watch it happen. In practice it is a well-defined sequence, and knowing the sequence makes it much easier to tell a thorough job from a rushed one — because the corners that get cut are always in the same place.
Stage 1 — Camera inspection and measurement
A self-levelling camera head runs the full lateral, from the cleanout to the connection at the public main, while a locator marks position and depth on the surface above. This establishes three things: what is wrong, exactly where, and whether the host pipe can take a liner at all.
It also establishes length and diameter, which is what the liner is cut and specified to. A liner is made for your pipe; it is not pulled off a shelf.
Stage 2 — Cleaning and descaling
This is the stage that gets skipped, and it is the stage that matters most. Resin bonds to the pipe wall. If that wall is coated in scale, grease or root hair, the resin bonds to the debris instead of the pipe — and the liner will eventually delaminate.
On the older cast iron common in Silver Spring, Bowie and Hyattsville, cleaning means mechanical descaling first: chain knockers strip decades of tuberculation back toward bare metal. Hydro jetting then flushes out everything that was knocked loose. On clay, jetting and root cutting are usually enough.
Stage 3 — Installing the liner
The liner is saturated with resin (the trade calls this wet-out) and then introduced into the pipe, either pulled into place or inverted in under pressure. Once positioned, a bladder inflates it so the liner presses firmly against the full circumference of the host pipe.
Pressure is held throughout. The liner has to be in continuous contact with the pipe wall while it hardens, or you get voids and wrinkles — both of which show up on the verification pass and both of which are grounds to redo the work.
Stage 4 — Curing
The resin is then cured, usually with hot water, steam or UV light depending on the system. Cure time varies with method, liner length and diameter, and ambient ground temperature — anywhere from under an hour to several hours.
This is the window when you cannot run water. Plan for it: fill a jug or two, and if you work from home, expect the bathroom to be out of service for the afternoon.
Stage 5 — Reinstatement and verification
If any branch lines join the run being lined, the liner will have sealed across them. A cutter guided from inside the pipe reopens each connection precisely.
Then a final camera pass, and a full-volume flow test. You should be given that footage. It is your pipe and your property, and having a recording of the finished line is exactly what you want in hand if you sell the house or ever need a second opinion.
What the finished line looks like
On camera the difference is unmistakable: a continuous, smooth, pale interior with no joints, no root hair and no rough scale. Because the new surface is smoother than the original cast iron ever was, a lined pipe frequently flows better than the pipe it replaced — even though the liner adds a small amount of wall thickness.
That is the part that surprises homeowners most. They expect to have traded diameter for durability, and instead they get both.